Method of flameproofing cellulosic textile material with phosphorous triisocyanate or phosphoryl triisocyanate and products produced thereby



METHOD 9F FLAMEPROOFING CELLULOSIC TEXTILE MATERIAL WITH PHOSPHOROUS TRIISOCYANATE R PHOSPHORYL TRIISO- CYANATE AND PRODUCTS PRODUCED THEREBY 12 Claims. (Cl. 8-116) This invention relates to the flameproofing of cellulosic materials, more particularly textiles and the like.

Most textiles will burn andflameproofing treatment is desirable, but in instances where fire hazards are abnormally great, or where major losses would be inflicted by a fire, it is especially advantageous to flameproof textile materials. 7 Curtains on windows immediately 'above kitchen ranges, restaurant draperies, and large stage curtains are examples of circumstances where flameproofing is especially desirable.

Flameproofing chemicals are generally designated as non-durable, semi-durable, or durable depending upon the number of washings or cleanings which the flameproofed material is able to undergo without losing its flame-resistant properties. Those agents which readily leach out of the textile, perhaps upon only a single washing or dry cleaning, are termed non-durable.

The compounds used in accordance with this invention are durable flameproofing agents. They are of superior activity when applied to cellulosic material as they chemically combine with certain active hydroxyl groups therein. Although these compounds are not novel, per se, their ability to impart flame-resistant properties to textiles has, to the best of my knowledge, not previously been known.

I have discovered that the compounds of the formula:

Phosphorous Phosphoryl triisocyanate triisocyanate and mixtures thereof, are able to impart excellent flameresistant and glow-resistant properties to normally combustible cellulosic textiles, without diminishing their tensile strength.

In practicing my invention, the amount of isocyanate combined with the textile material will depend upon the type of material, i.e., the natural tendency of the material to resist flaming or glowing. This can be readily determined by simple investigation for a particular set of circumstances. I prefer to add on about weight percent to 25 weight percent of the isocyanate to cellulosic materials. I

The adding on can be carried out in the manner generally known to the art. The isocyanate is suitably dissolved in a solvent boiling below about 150 C., for example, benzene or a lower alkyl benzene such as toluene, ethylbenzene or a xylene, or a lower dialkyl ether such as diethyl ether, diisopropyl ether or dibutyl ether, to the extent of about 5 to 15 weight percent. After passing the textile through such a bath it is dried and cured. The curing is done by heating the dried, impregnated textile at about 200 to 300 F. for at least two minutes, generally from two to ten minutes. During this curing operation, the isocyanate chemically adds to the cellulosic material, thus becoming permanent or durable.

nited States Patent 0 2,898,180 Patented Aug. 4, 1959 ice The following examples further illustrate a method of putting this invention into practice.

Example I A 10 weight percent solution. of phosphoryl triisocyanate in benzene was padded onto a section of Indian Head cotton. The wet pickup was 84.2 percent. The treated cloth was then driedfor 4 minutes at 220 F. and the dry pickup was then 13.25 percent. The material was cured by passing it over a second drier. While in contact with the second drier, a second piece of cloth was used to cover the treated section in order to maintain a sufficiently high temperature for curing. The contact time with the drier was from 2 to 3 minutes, and the temperature was 265 F.

. The flammability of the treated cloth was tested according to the American Association of Textile Chemists and Colorists Method 33-52, ASA Designation Ll4.69- 1952. In this test a strip of cloth, usually six inches long and about two inches wide, is held in a frame at an angle of about 45 from vertical. The lower edge of the cloth is exposed to a controlled C.P. butane flame for a standard time, usually one second. The test then determines the length of time required for the flame of the burning cloth to reach the upper edge or the cloth strip after the latter has been ignited by the butane flame.

When the above test was performed on a strip of the cotton treated according to this example, it was found that the butane flame would not ignite the sample after being in contact with the latter for seconds. At the end of this time the material which had been in the flame was charred and disintegrated; however, the cloth above this section was unaffected. This material was considered to be completely flameproof.

To test the durability of the flame-proofing agent, a section of the treated material was washed in an aqueous solution containing 10 weight percent sodium carbonate and 0.1 weight percent of a surfactant. It was then found that a one second flame exposure was again insuflicient to ignite the cotton cloth, and that 5 seconds were required to impart a flame thereto. then required 54 seconds to reach the top of the six inch test strip. In view of the 5 second exposure to flame required to cause burning, this material is still considered to be excellently flame-proofed.

By way of comparison, when an untreated portion of the same Indian Head cotton was exposed to the flame for one second it ignited and burned completely in 21.5 seconds.

Example 11 A second section of Indian Head cotton was padded with a 10 weight percent solution of phosphorous triisocyanate in benzene. The wet pickup was 85.6 percent and the dry pickup was 5.2 percent. The flammability, glowresistance and durability of this material was substantially the same as that of the material treated with the phosphoryl triisocyanate.

These isocyanates can be prepared by various methods described in the literature. For example, the phosphoryl compound can be made by reacting silver cyanate and phosphoryl trichloride. Likewise the reaction of phosphoroustrichloride and silver cyanate yields phosphorous triisocyanate.

I claim: 7

l. Cellulosic textile material resistant to combustion which has been rendered resistant to combustion by impregnating cellulosic textile material containing active hydroxyl groups with a solution, in an inert organic solvent boiling below about C., of a compound selected from the group consisting of phosphorous triisocyanate and phosphoryl triisocyanate in amount such that the textile material impregnated upon removal of the solvent contains from 5 to 25 weight percent of said compound, based on the weight of the textile material impregnated, and thereafter heating the impregnated textile material at a temperature within the range from about 200 F. to 300 F. until the solvent is removed and the textile material impregnated chemically combines with said compound.

' 2. The article of claim 1 wherein said material is cotton.

3. The article of claim 1 wherein said compound is phosphorous triisocyanate.

4. The article of claim 1 wherein said compound is phosphoryl triisocyanate. 9

5. The article of claim 1 wherein said material is cotton and wherein said compound is phosphorous triisocyanate.

6. The article of claim 1 wherein said material is cotton and wherein said compound is phosphoryl triisocyanate.

7. A method for rendering cellulosic textile material containing active hydroxyl groups resistant to combustion which comprises impregnating the textile material with a solution, in an inert organic solvent boiling below about 150 C., of a compound selected from the group consisting of phosphorous triisocyanate and phosphoryl triisocyanate in an amount such that said textile material upon removal of the solvent contains from 5 to 4 25 weight percent of'said compound, based upon the weight of said textile material, and thereafter heating the impregnated textile material at a temperature within the range from about 200 F. to 300 F. until the solvent is removed and said textile material chemically combines with said compound.

8. The method of claim 7 wherein said material is cotton.

9. The method of claim 7 wherein said compound is phosphorous triisocyanate.

10. The method of claim 7 wherein said compound is phosphoryl triisocyanate.

11. The method of claim 7 wherein said material is cotton and wherein said compound is phosphorous triisocyanate.

12. The method of claim 7 wherein said material is cotton and wherein said compound is phosphoryl triisocyanate.

References Cited in the file of this patent UNITED STATES PATENTS 2,637,704 Hurley May 9, 1953 2,648,597 Nielsen Aug. 11, 1953 2,661,263 Neilsen Dec. 1, 1953 2,661,342 Malowan Dec. 1, 1953 2,691,567 Kvalnes Oct. 12, 1954 2,782,133 Vallette Feb. 19, 1957 

1. CELLULOSIC TEXTILE MATERIAL RESISTANT TO COMBUSTION WHICH HAS BEEN RENDERED RESISTANT TO COMBUSTION BY IMPREGNATING CELLULOSIC TEXTILE MATERIAL CONTAINING ACTIVE HYDROXYL GROUPS WITH A SOLUTION, IN AN INERT ORGANIC SOLVENT BOILING BELOW 150* C., OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF PHOSHOROUS TRIISOCYANATE AND PHOSPHORYL TRIISOCYANATE IN AMOUNT SUCH THAT THE TEXTILE MATERIAL IMPREGNATED UPON REMOVAL OF THE SOLVENT CONTAINS FROM 5 TO 25 WEIGHT PERCENT OF SAID COMPOUND, BASED ON THE WEIGHT OF THE TEXTILE MATERIAL IMPREGNATED, AND THEREAFTER HEATING THE IMPREGNATED TEXTILE MATERIAL AT A TEMPERATURE WITHIN THE RANGE FROM ABOUT 200* F. TO 300* F. UNTIL THE SOLVENT IS REMOVED AND THE TEXTILE IMPREGNATED CHEMICALLY COMBINES WITH SAID COMPOUND. 